Membrane Suction Pump Unit

ABSTRACT

A membrane suction pump unit has a dimensionally stable membrane frame ( 1 ), a dimensionally stable monobloc membrane cover ( 3 ), which has a pump chamber ( 31 ) with a floor region and a side wall ( 36 ) encircling the floor region and widening outwards away from the floor region, and a monobloc pump membrane ( 2 ), which has a membrane plate ( 20 ), a flexible membrane piston ( 21 ), at least one inlet valve flap ( 23 ) and at least one outlet valve flap ( 24 ). The membrane plate ( 20 ) is arranged between the membrane frame ( 1 ) and the membrane cover ( 3 ), and membrane frame ( 1 ), pump membrane ( 2 ) and membrane cover ( 3 ) are connected to one another by means of connecting elements ( 15, 15′, 15 ″) in a preset position. The membrane piston ( 21 ) passes through the membrane frame ( 1 ), and the membrane piston ( 21 ) covers a pump chamber ( 31 ) of the membrane cover ( 3 ). According to the invention, there are more than three connecting elements ( 15, 15′, 15 ″), forming a material and/or positive fit.

TECHNICAL FIELD

The invention relates to a membrane suction pump unit according to thepreamble of claim 1.

STATE OF THE ART

A generic membrane pump unit as part of a breast pump is known forexample from U.S. Pat. No. 4,964,851. The breast pump has anelectromotor, a piston rod powered by the motor, and a connected pumpmembrane. The pump membrane is held in a membrane frame and togetherwith a membrane cover forms a pump chamber. In the commerciallyavailable pump, the membrane frame, pump membrane and membrane cover areconnected to one another by means of a press connection, with three pinsof the membrane frame being held frictionally engaged in correspondingopenings in the membrane cover.

U.S. Pat. No. 7,070,400 also discloses the same type of membrane pumpunit of a suction pump, where the membrane has a membrane piston withrear depressions. The membrane cover defines a space with a flat floorsection and a circular side wall widening conically outwards. This spaceis covered by the membrane piston and forms the pump chamber.

EP 0 744 180 likewise describes a membrane suction pump which nowhowever is suited for simultaneous use of two suction connectors.

WO 2006/032156 also shows a membrane pump with three housing parts whichare interconnected by snap elements.

DESCRIPTION OF THE INVENTION

It is an object of the invention to provide a membrane suction pump unitwhich has increased processing stability.

This object is achieved by a membrane suction pump unit having thefeatures of claim 1.

The inventive membrane suction pump unit has a dimensionally stablemembrane frame, a dimensionally stable monobloc membrane cover, whichhas a pump chamber with a floor region and a side wall encircling thefloor region and widening outwards away from the floor region, and witha monobloc pump membrane which has a membrane plate, a flexible membranepiston, at least one inlet valve flap and at least one outlet valveflap, and a monobloc pump membrane with a membrane plate, a flexiblemembrane piston and with at least one inlet valve flap and at least oneoutlet valve flap, the membrane plate being arranged between themembrane frame and the membrane cover, and membrane frame, pump membraneand membrane cover being connected to one another by means of connectingelements in a preset position. The membrane piston passes through themembrane frame and, together with the membrane cover, it forms a pumpchamber or covers the pump chamber. According to the invention, thereare more than three connecting elements, forming a material and/orpositive fit.

The connecting elements connect the membrane frame and the membranecover with each other and the pump membrane is hold between membraneframe and membrane cover. The connecting elements can penetrate the pumpmembrane or the pump membrane can be hold between them.

The material and/or positive fit ensure that the connection cannot bebroken automatically or by vibrations. In the case of the previouslyused frictional engagement, it is possible for the connection betweenthe individual parts, i.e. frame, membrane and cover, to be broken, inparticular if the pump triggers vibrations in the range of the naturaloscillation of the device.

Assembly is also simplified. Assembly is usually carried out manually.This proves easier in practice if there are several connecting elementsand thus positions than when three corresponding positions have to bemanually brought into alignment. The danger of jamming is herebylessened.

Although using more than three connecting elements would actually resultin static uncertainty, it has been shown that improved overalldimensional stability is attained. The result of using more than three,in particular from six to twelve, connecting elements is thus greaterstability and overall rigidity of the device. As a result, membranecover and membrane frame can distort less, and the unit exhibitsincreased tightness, or the danger of the unit becoming leaky due tofluctuations in temperature, vibrations or material fatigue isminimized. Preferably, nine connecting elements are used, which aredistributed around the edge area.

The use of several connecting elements also increases the characteristicfrequency of the system. Acoustic properties are improved, and thetendency to background noise during the pumping procedure is reduced.

The connecting means are preferably pins which are fixed in the seats.They can for example be bonded, welded or riveted. Positive lockingelements, for example snap hooks, pine-tree snap locks and similarmeans, can also be used in place of pins, however.

It is also possible to use positive and material locking, for examplevia welded pine-tree snap locks.

In a preferred embodiment, the membrane cover has over its entiresurface an approximately uniform thickness.

This also prevents warping and deformation and boosts tightness.

The inventive suction pump unit can be manufactured cost-effectively, inparticular because it comprises only three parts, of which the twodimensionally stable parts, membrane frame and membrane cover, can bemade from plastic in an injection moulding process, and the pumpmembrane can preferably be made from liquid silicone in an injectionmoulding process.

This suction pump unit is preferably used in breast pumps for expressingbreast milk. However, it is also suitable for other suction pumps, forexample drainage pumps.

Further advantageous embodiments will emerge from the dependent claims.

BRIEF DESCRIPTION OF THE DRAWINGS

The subject matter of the invention will be explained hereinbelow by wayof a preferred exemplary embodiment, illustrated in the attacheddrawings in which:

FIG. 1 shows a perspective exploded view of the inventive membranesuction pump unit from above;

FIG. 2 shows a perspective exploded view of the membrane suction pumpunit as per FIG. 1 from below;

FIG. 3 shows a perspective illustration of the membrane frame;

FIG. 4 shows a perspective illustration of the membrane cover in asecond embodiment;

FIG. 5 shows a perspective illustration of a fastening pin;

FIG. 6 shows a membrane frame with electromotor in an exploded view, and

FIG. 7 shows a perspective exploded view of the membrane suction pumpunit in a further embodiment.

WAYS OF CARRYING OUT THE INVENTION

Direction particulars such as above and below are used hereinafter.These refer solely to the arrangement of the individual parts in thefigures and do not refer to the position of installation of theinventive membrane suction pump unit in a suction pump.

The inventive membrane suction pump unit as per FIG. 1 has a membraneframe 1, a pump membrane 2 and a membrane cover 3. All these parts arepreferably of monobloc design. Membrane frame 1 and membrane cover 3 aredimensionally stable and preferably manufactured in an injectionmoulding process from plastic, for example thermoplastic, such aspolyester. The pump membrane 2 is also monobloc and made in an injectionmoulding process from liquid silicone.

The membrane frame 1 has a plane-parallel base plate 10 with a roundthrough hole 11. Formed at one end of the base plate 10 and verticalthereto is a stop plate 16. This stop plate 16 has a pump unit seat 19,in which a valve unit, not illustrated here, for example as disclosed inU.S. Pat. No. 4,964,851, is housed. In the seat 19 there is a suctionopening 18 in the stop plate 16, which merges into an air intake 18′ onthe rear side visible in FIG. 2.

On the side of the base plate opposite the stop plate 16 there is anelectromotor 4, illustrated in FIG. 6, which is connected to the laterdescribed piston connector 26 of the pump membrane via a piston rod, notillustrated.

As is evident from FIG. 2, the stop plate 16 is provided with an inletopening 13, pointing to the pump membrane 2. This inlet opening 13 isconnected to the exterior via a connecting channel 13″ and an inletchannel 13′ connected to the latter. This is shown in FIG. 3.

The base plate 10, as is again now evident in FIG. 1, also has a channel10′ on its surface, which channel terminates in the stop plate 16 in athrough hole 10″. This serves to assemble a vacuum adjustment pin, notillustrated here.

On the underside of the base plate 10, evident in FIG. 2, is a firstcircular sealing groove 12. It encloses the through hole 11, the inletopening 13 and a groove forming an outlet channel 14. This outletchannel is arranged on the side of the through hole 11 diametricallyopposite the inlet opening 13 and terminates on a side edge of the baseplate 10. At this end the base plate has an upper channel connection 17in the form of a protruding nose having a U-shaped longitudinal section.

On the base plate 10, connecting elements are formed that projectdownwards to the pump membrane. In this embodiment these connectingelements are substantially cylindrical pins 15, 15′, 15″, although otherconnecting elements such as snap lock elements can be present. In thiscase the snap lock elements are formed preferably on the outer edges ofthe base plate. This second embodiment is illustrated in FIG. 7. Formedon the membrane frame 1, on the circular front faces, are hooks 151, andon the membrane cover 3 there are matching snap-in shackles 152. Thepump membrane 2 needs no connecting elements, rather it is simply heldclamped between membrane cover 3 and membrane frame 1.

The pins 15, 15′, 15″ according to the first embodiment are arrangedpreferably exclusively in the edge region of the base plate 10 andoutside the sealing groove 12, distributed over the periphery. There aremore than three pins 15, 15′, 15″. In the illustrated example there arenine pins, with preferably six to twelve pins being used.

In a simplified embodiment, all pins are configured the same length andsame thickness. However, pins of varying shape may also be used, as isthe case here. Some pins, preferably at least two opposing pins 15″, aredesigned as positioning pins and have a basic cylindrical body and atapering or tapered tip. Some pins, here first pins 15, have a largerdiameter than second pins 15′. The pins 15, 15′, 15″ can also beequipped with vertical ribs 150, as shown in FIG. 5.

The length of the pins 15, 15′, 15″ is such that they pass through thepump membrane 2 arranged behind and project at least partially into themembrane cover 3 or likewise pass preferably completely through this andterminate at its opposite surface.

It is also possible that the pins are formed on the membrane cover orthat some of the pins are arranged on the membrane frame and some on themembrane cover, as illustrated in FIG. 4.

The pump membrane 2 arranged beneath the base plate 10 has a likewisesubstantially plane-parallel membrane plate 20. This membrane plate 20has approximately the same base surface as the base plate 10. In themiddle region of the membrane plate 20, the latter merges into amembrane piston 21, which projects upwards of the membrane plate 20 tothe base plate 10. The membrane piston 21 is designed as a cap shape,and preferably has annular circular recesses. Formed in the middle ofthe membrane piston 20 is the piston seat 26 in the form of a hollowcylinder. The piston can easily plug into this seat 26 and is heldtherein positively and non-positively.

Located on one side of the membrane piston 21 is a horseshoe-shapedinlet valve flap 23. On the opposite side of the membrane piston 21, themembrane plate 20 has two likewise substantially horseshoe-shaped outletvalve flaps 24 arranged at a distance apart. There can also be more thanone or fewer than two valve flaps 23, 24.

The membrane plate 20 has an upper sealing lip 22 which, on the top sidefacing the base plate 10, encloses the membrane piston 21 and the valveflaps 23, 24, and which is self-contained and projects upwards.

The membrane plate 20 similarly has on its underside facing the membranecover 3 a circular lower sealing lip 28, which likewise enclosesmembrane piston 21 and valve flaps 23, 24 and projects downwards. Thetwo sealing lips 22, 28 are preferably congruent.

It is however also possible that only one of the two sealing lips ispresent, or that they are not congruent. Instead of the sealing lips,sealing grooves could also be in place, and the membrane cover and/orthe membrane frame are provided with a corresponding sealing lip oredge.

Formed on a side edge of the membrane plate 20 is a protruding nose 27projecting over the edge, but otherwise flush with the top side andunderside of the plate 20.

Outside the sealing lips 22, 28 the membrane plate 20 is penetrated byfirst and second fastening holes 25, 25′, the diameters of whichpreferably correspond to the associated pins 15, 15′, 15″ of the baseplate 10, or are slightly larger.

The membrane cover 3 has a cover plate 30, the top side of whichpointing to the pump membrane 2 is likewise designed substantiallyplane. Its underside on the other hand is structured as is describedhereinbelow. Formed in the middle of the cover plate 30 is a pumpchamber 31, which has a floor region at the same level as the surface ofthe remaining cover plate 30 and a raised circular side wall 36, theside wall being designed to incline upwards and outwards, so that theopening widens out over the floor region. The side wall 36 can bedesigned straight oblique or, as shown here, curved.

The side wall 36 is penetrated by at least one inlet channel, here threeinlet channels 33′ running parallel to one another. These channels 33come from an inlet basin 33, which is designed as a recess in the coverplate 30 and terminate in the floor region at a distance from the sidewall 36. On the opposite side, the side wall 36 is pierced by at leastone, here two outlet channels 34 running radially outwards andterminating at a distance outside the side wall 36 in the cover plate30.

Pump chamber 31, inlet basin 33 and both inlet and outlet channels 33′,34 are enclosed by a fully circular second sealing groove 32.

Formed at one side edge of the cover plate 30 is a protruding nose,which forms a lower channel connector 37 with upright side walls. Thislower channel connector 37 forms the counterpart to the upper channelconnector 17 and thus preferably has a U-shaped longitudinal section.The abovementioned protruding nose 27 of the pump membrane 2 is of sucha size that it corresponds to the base area of the channel connectors17, 37 and is held therein.

Outside the second sealing groove 32 there are seat openings 35, 35′,35″ which take up the positioning and fastening pins 15, 15′, 15″. Theseopenings 35, 35′, 35″ are flush with the top side of the cover plate 30.On the underside of same, however, they are formed as uptake sockets andare connected to one another preferably via reinforcing ribs 38. Thesockets also can be provided on the inside with vertical ribs or havepositioning aids. The sockets preferably have an unround inner crosssection and are preferably polygonal. This again increases the stabilityof the connection with the pins.

As is evident from FIG. 2, the underside of the cover plate 30 isdesigned structured as a negative to the elements formed in the top sideof the cover plate. This means that the recesses of the top side aredesigned extending downwards on the underside and the elevations of thetop side are correspondingly sunk in the underside. Here the cover plate30 has a thickness approximately uniform over the entire base area orover a large part of the base area. This does not however apply at allpoints. By way of example, this does not apply in the area of thereinforcing links between the sockets or between other possibleelevations in the underside. This type of structured cover plate canalso be employed in suction pump units whose connecting elements connectthe individual parts frictionally engaged or non-positively.

When the inventive unit is in the assembled state, the pump membrane 2or its membrane plate 20 is now clamped in between the base plate 10 ofthe membrane frame 1 and the cover plate 30 of the membrane plate 3. Atthe same time the membrane piston 21 passes through the through hole 11and because of the motor can move up and down. The membrane piston 21covers the pump chamber 31 and, since the outer diameter of the membranepiston 21 is the same size as or greater than the outer diameter of theside wall 36 of the pump chamber 31, it seals the chamber 31 except forthe inlet and outlet channels 33′, 34.

The fastening pins 15, 15′, 15″ pass through the fastening holes 25, 25′of the pump membrane 2 and are plugged positively into the uptakesockets 35, 35′, 35″ of the membrane cover 3. In addition, they arestuck therein by means of adhesive or are connected otherwise to form amaterial or positive fit. By way of example, they can beultrasound-welded, vibration-welded, welded at high frequency orultrasound-riveted.

Due to this precise positioning of the three individual parts, the inletopening 13 lies above the inlet valve flap 23 and the latter lies abovethe inlet basin 33. The outlet channel 14 of the membrane frame 1 liesabove the outlet valve flaps 24 and the latter lie above the outletchannels 34 of the membrane cover.

The upper and lower sealing lips 22, 28 lie in the first and secondsealing grooves 12, 32, respectively, and thus seal the areas in eachcase enclosed thereby to the exterior.

The side walls of the lower channel connector 37 resiliently enclose theside walls of the upper channel connector 17 and thus form a tightpositive and frictional connection. The nose 27 of the pump membrane 2lies on the lower channel connector 37.

The membrane piston 21 passes through the through hole 11 of the baseplate 10 when the unit is in the assembled state.

LEGEND

-   -   1 membrane frame    -   10 base plate    -   10′ channel    -   10″ through hole    -   11 through hole    -   12 first sealing groove    -   13 inlet opening    -   13′ inlet channel    -   13″ connection channel    -   14 outlet channel    -   15 first fastening pin    -   15′ second fastening pin    -   15″ positioning pin    -   150 vertical ribs    -   151 hook    -   152 snap-in shackle    -   16 stop plate    -   17 upper channel connector    -   18 suction opening    -   18′ air intake    -   19 pump unit seat    -   2 pump membrane    -   20 membrane plate    -   21 membrane piston    -   22 upper sealing lip    -   23 inlet valve flap    -   24 outlet valve flap    -   25 first fastening hole    -   25′ second fastening hole    -   26 piston connector    -   27 nose    -   28 lower sealing lip    -   3 membrane cover    -   30 cover plate    -   31 pump chamber    -   32 second sealing groove    -   33 inlet basin    -   33′ inlet channel    -   34 outlet channel    -   35 first seat opening    -   35′ second seat opening    -   35″ positioning hole    -   36 side wall    -   37 lower channel connector    -   38 reinforcing rib    -   4 electromotor

1. Membrane suction pump unit with a dimensionally stable membraneframe, a dimensionally stable monobloc membrane cover, which has a pumpchamber with a floor region and a side wall encircling the floor regionand widening outwards away from the floor region, and with a monoblocpump membrane, which has a membrane plate, a flexible membrane piston,at least one inlet valve flap and at least one outlet valve flap, themembrane plate being arranged between the membrane frame and themembrane cover, and membrane frame, pump membrane and membrane coverbeing connected to one another by means of connecting elements in apreset position, the membrane piston passing through the membrane frame,and the membrane piston covering a pump chamber of the membrane cover,wherein there are more than three connecting elements and in that theyform a material and/or positive fit.
 2. Suction pump unit according toclaim 1, in which the connecting elements are plugged into seat openingsof the membrane frame and/or the membrane plate and are welded, rivetedor bonded to the membrane frame or the membrane plate.
 3. Suction pumpunit according to claim 1, in which there are six to twelve, preferablynine connecting elements.
 4. Suction pump unit according to claim 1, inwhich the connecting elements pass through the pump membrane exclusivelyin its outer edge region.
 5. Suction pump unit according to claim 1, inwhich the membrane cover has a thickness which is uniform overapproximately its entire surface.
 6. Suction pump unit according toclaim 1, in which the connecting elements are pins or snap-in elements.7. Suction pump unit according to claim 1, in which at least some of theconnecting elements are arranged on the membrane frame.
 8. Suction pumpunit according to claim 1, in which at least some of the connectingelements are arranged on the membrane cover.
 9. Suction pump unitaccording to claim 1, in which membrane cover and membrane frame aremade from plastic and the connecting elements are connected integrallyto the membrane cover or the membrane frame.
 10. Suction pump unitaccording to claim 1, in which at least some of the connecting elementsare provided with longitudinal ribs.
 11. Suction pump unit according toclaim 1, in which at least some of the connecting elements are providedwith a positioning aid.
 12. Suction pump unit according to claim 1, inwhich the membrane cover and/or the membrane frame has socket-like seatsfor taking up the connecting elements.
 13. Suction pump unit accordingto claim 12, in which the socket-like seats are interconnected by ribs.14. Suction pump unit according to claim 12, in which the seats have anunround, in particular polygonal, cross-section.
 15. Suction pump unitaccording to claim 1, in which the membrane plate has inlet and outletvalve flaps and on one side has a first sealing lip, the sealing lipcompletely encircles the membrane piston, the inlet and outlet valveflaps are located inside a region enclosed by the sealing lip, and theconnecting elements pass through the membrane plate outside thiscircular sealing lip.
 16. Suction pump unit according to claim 15, inwhich the membrane plate has, on the opposite side, a second sealing lipwhich cooperates with the first sealing lip and likewise encloses themembrane piston and the inlet and outlet valve flaps.
 17. Suction pumpunit according to claim 16, in which the first and second sealing lipsare congruent.
 18. Suction pump unit according to claim 1, in which thepump membrane is designed in one piece from a flexible material. 19.Membrane suction pump unit with a dimensionally stable membrane frame, adimensionally stable monobloc membrane cover, which has a pump chamberwith a floor region and a side wall encircling the floor region andwidening outwards away from the floor region, and with a monobloc pumpmembrane, which has a membrane plate, a flexible membrane piston, atleast one inlet valve flap and at least one outlet valve flap, themembrane plate being arranged between the membrane frame and themembrane cover, and membrane frame, pump membrane and membrane coverbeing connected to one another by means of connecting elements in apreset position, the membrane piston passing through the membrane frame,and the membrane piston covering a pump chamber of the membrane cover,characterized in that there are more than three connecting elements. 20.Membrane suction pump unit with a dimensionally stable membrane frame, adimensionally stable monobloc membrane cover, which has a pump chamberwith a floor region and a side wall encircling the floor region andwidening outwards away from the floor region, and with a monobloc pumpmembrane, which has a membrane plate, a flexible membrane piston, atleast one inlet valve flap and at least one outlet valve flap, themembrane plate being arranged between the membrane frame and themembrane cover, and membrane frame, pump membrane and membrane coverbeing connected to one another by means of connecting elements in apreset position, the membrane piston passing through the membrane frame,and the membrane piston covering a pump chamber of the membrane cover,characterized in that the connecting elements form a material and/orpositive fit.
 21. Membrane suction pump unit with a dimensionally stablemembrane frame, a dimensionally stable monobloc membrane cover, whichhas a pump chamber with a floor region and a side wall encircling thefloor region and widening outwards away from the floor region, and witha monobloc pump membrane, which has a membrane plate, a flexiblemembrane piston, at least one inlet valve flap and at least one outletvalve flap, the membrane plate being arranged between the membrane frameand the membrane cover, and membrane frame, pump membrane and membranecover being connected to one another by means of connecting elements ina preset position, the membrane piston passing through the membraneframe, and the membrane piston covering a pump chamber of the membranecover, characterized in that the membrane cover has a thickness which isuniform over approximately its entire surface.
 22. Suction pump unitaccording to claim 21, in which the membrane cover has an undersidewhich faces away from the pump membrane and which is designedstructured.